Well, a friend asked TLP (the laughing place) on Twitter how it had been confirmed, since they didn’t really specify the source. They responded saying they had emailed Disney asking if they could confirm the rumour, to which the answer had been “yes”.
Plus a minor insider confirmed the plans for the re-do of the security outside MK (like making the security checks more permanent structures etc) had included changes to the path round to the canal.
In those plans, which are available, although they don’t show much on the path itself, there is what looks to be a security checkpoint near the end of the path, kind of between the monorail and the lagoon.
So, yes it seems like it. I have to say I was really sceptical, but happy to be proved wrong.